rework the password subsystem

[unix-history] / usr / src / lib / libc / gen / getpwent.3

.\" Copyright (c) 1988 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)getpwent.3  6.7 (Berkeley) %G%
.\"
.TH GETPWENT 3  ""
.AT 3
.SH NAME
getpwent, getpwnam, getpwuid, setpassent, setpwent,
endpwent \- get password file entries
.SH SYNOPSIS
.nf
.ft B
#include <sys/types.h>
#include <pwd.h>

struct passwd *getpwent(void);
struct passwd *getpwnam(char *login);
struct passwd *getpwuid(uid_t uid);
int setpassent(int stayopen);
int setpwent(void);
void endpwent(void);
.ft R
.fi
.SH DESCRIPTION
.IR Getpwent ,
.IR getpwuid ,
and
.I getpwnam
each return a pointer to a structure containing the broken-out
fields of a line in the password file.  This structure is defined
by the include file
.IR < pwd.h > ,
and contains the following fields:
.PP
.RS
.nf
struct passwd {
       char    *pw_name;                       /* user name */
       char    *pw_passwd;             /* encrypted password */
       uid_t   pw_uid;         /* user uid */
       gid_t   pw_gid;         /* user gid */
       time_t  pw_change;      /* password change time */
       char    *pw_class;              /* user access class */
       char    *pw_gecos;              /* Honeywell login info */
       char    *pw_dir;                        /* home directory */
       char    *pw_shell;              /* default shell */
       time_t  pw_expire;      /* account expiration */
};
.fi
.RE
.PP
These fields are more completely described in
.IR passwd (5).
.PP
.I Getpwnam
and
.I getpwuid
search the password database for a matching user name or user uid,
respectively, always returning the first one encountered.
.PP
.I Getpwent
sequentially reads the password database and is intended for programs
that wish to process the complete list of users.
.PP
.I Setpassent
accomplishes two purposes.
First, it causes
.I getpwent
to ``rewind'' to the beginning of the database.
Additionally, if
.I stayopen
is non-zero, file descriptors are left open, significantly speeding
up subsequent accesses for all of the routines.
(This latter functionality is unnecessary for
.I getpwent
as it doesn't close its file descriptors by default.)
.PP
It is dangerous for long-running programs to keep the file descriptors
open the database will become out of date if it is updated while the
program is running.
.PP
.I Setpwent
is identical to
.I setpassent
with an argument of zero.
.PP
.I Endpwent
closes any open files.
.PP
These routines have been written to ``shadow'' the password file, e.g.
allow only certain programs to have access to the encrypted password.
If the process which calls them has an effective uid of 0, the encrypted
password will be returned, otherwise, the password field of the retuned
structure will point to the string ``*''.
.SH FILES
/var/db/pwd.db                  The insecure password database file
.br
/var/db/spwd.db         The secure password database file
.br
/etc/master.passwd              The current password file
.br
/etc/passwd                     A Version 7 format password file
.SH "SEE ALSO"
getlogin(3), getgrent(3), passwd(5), pwd_mkdb(8), vipw(8)
.SH DIAGNOSTICS
The routines
.IR getpwent ,
.IR getpwnam ,
and
.IR getpwuid ,
return a null pointer on EOF or error.
.I Setpassent
and
.I setpwent
return 0 on failure and 1 on success.
.I Endpwent
has no return value.
.SH BUGS
All information is contained in a static buffer which is overwritten
by each new call.
It must be copied elsewhere to be retained.
.PP
The routines
.IR getpwent ,
.IR endpwent ,
.IR setpassent ,
and
.IR setpwent
are fairly useless in a networked environment and should be
avoided, if possible.
.SH COMPATIBILITY
The historic function
.IR setpwfile ,
which allowed the specification of alternate password databases,
has been deprecated and is no longer available.